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Analog Devices Inc. LTC3126IUFD#TRPBF
- Part No.:
- LTC3126IUFD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LTC3126IUFD#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 2.5A 28QFN
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LTC3126IUFD#TRPBF from Analog Devices (formerly Linear Technology) is a 42V, 2.5A synchronous step-down regulator with integrated no-loss PowerPath™ for seamless dual-input power source management. It supports pin-selectable priority and ideal diode-OR modes, features 2µA Burst Mode® quiescent current, 200kHz–2.2MHz programmable switching frequency, and operates across 2.4V–42V input range to deliver 0.818V–VIN output. It is used in automotive battery backup systems where automatic switchover between main and backup supplies must occur without output rail disturbance.
For engineers reviewing the LTC3126IUFD#TRPBF datasheet, LTC3126IUFD#TRPBF pinout, LTC3126IUFD#TRPBF application, or LTC3126IUFD#TRPBF equivalent, key selection criteria include dual-input UVLO programmability via VSET1/VSET2, 60ns minimum on-time for high VIN/VOUT ratios, thermal performance in the 4mm × 5mm QFN package, and compatibility with EXTVCC bootstrapping for efficiency optimization at high input/low output conditions.
Technical Context
The LTC3126IUFD#TRPBF implements current-mode control with independent input validation comparators, programmable UVLO thresholds (2.34V fixed + adjustable up to 20V), and fast automatic switchover between VIN1 (priority) and VIN2 (backup). Its PowerPath architecture eliminates hold-up capacitors by maintaining regulation during transitions.
It integrates dual high-side (200mΩ) and low-side (70mΩ) MOSFETs, supports external synchronization via PWM/SYNC, and includes dedicated BST1/COM1 and BST2/COM2 charge pump rails for gate drive. The device maintains 1µA shutdown current and provides open-drain status signals (VALID1, VALID2, PRIORITY, PGOOD) with 70Ω pull-down resistance.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.4V to 42V - supports automotive transients (42V), supercapacitors, multicell batteries, and unregulated adapters. |
| Output Current | Up to 2.5A continuous - sufficient for powering FPGA I/O banks, microcontroller cores, or industrial sensors. |
| Quiescent Current | 2µA in Burst Mode - enables multi-year operation from energy-harvesting or backup sources. |
| Switching Frequency | 200kHz to 2.2MHz (RT-programmable) - allows optimization of size (high fSW) vs. efficiency (low fSW). |
| Feedback Voltage | 818mV ±12mV - sets precise output voltage with standard resistor dividers; supports 0.818V–VIN range. |
| Minimum On-Time | 46ns - enables high step-down ratios (e.g., 24V→3.3V at 2MHz) without pulse skipping. |
| Package | 28-lead 4mm × 5mm QFN - thermally enhanced with exposed PGND pad for ≤34°C/W θJA. |
Pinout & Package
Package: 28-lead (4mm × 5mm) plastic QFN with exposed PGND pad (Pin 29), rated for –40°C to 125°C operating junction temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN1 / Pin 25 | Priority input Kelvin sense | Low-impedance connection to PVIN1; bypassed with 0.1µF capacitor to minimize noise coupling into UVLO comparator. |
| PVIN1 / Pin 24 | Priority input power rail | Main high-current path for priority source; requires ≥4.7µF ceramic bypass to ground and Schottky protection against inductive shorts. |
| VIN2 / Pin 26 | Secondary input Kelvin sense | Low-impedance connection to PVIN2; bypassed with 0.1µF capacitor for accurate secondary input validation. |
| PVIN2 / Pin 13 | Secondary input power rail | High-current path for backup source; requires ≥4.7µF ceramic bypass and optional Schottky diode to ground. |
| DIODE / Pin 23 | Mode select logic input | High = ideal diode-OR (auto-select highest valid input); Low = priority mode (VIN1 first, fallback to VIN2 only on UVLO). |
| VSET1 / Pin 5, VSET2 / Pin 6 | UVLO threshold programming | Voltage divider from VREF sets input-specific UVLO (0–20V range); internal 2.34V threshold remains active if pins grounded. |
| PGOOD / Pin 11 | Open-drain output good indicator | Asserts low if VOUT deviates >8.7% below or >9.8% above regulation; also low during disable or startup. |
| PRIORITY / Pin 12 | Open-drain priority channel indicator | Asserts low only when enabled and buck is actively sourcing from VIN1/PVIN1 - confirms priority path engagement. |
Key Features
| Feature | Design Value |
|---|---|
| No-loss PowerPath™ architecture | Eliminates need for hold-up capacitors and prevents output rail droop during input switchover (e.g., automotive ignition loss → battery takeover in <50µs). |
| Programmable dual-input UVLO | VSET1/VSET2 pins allow independent, resistor-programmed undervoltage lockout thresholds per input - critical for mismatched sources like 12V battery + 24V supply. |
| Burst Mode® operation | Reduces no-load input current to 2µA while maintaining regulation - extends runtime in always-on backup systems powered by supercapacitors. |
| EXTVCC bootstrapping | Enables VCC rail to be powered from regulated output (e.g., 3.3V), cutting quiescent current and improving efficiency in high-VIN/low-VOUT applications. |
| 60ns minimum on-time | Supports high-frequency, high-ratio conversion (e.g., 36V→3.3V at 2MHz) without pulse-skipping instability or audible noise. |
Applications
| Automotive Battery Backup | Industrial Uninterruptible Power |
|---|---|
Use Scenario: Vehicle infotainment system powered from 12V battery with cold-crank backup during engine start. IC Role / Device Role / Timing Role: LTC3126IUFD#TRPBF acts as dual-input buck controller managing seamless transition from alternator (VIN1) to battery (VIN2) during cranking-induced voltage sag. Use Value: Maintains 5V/2.5A output without brownout using priority mode and 2.34V fixed UVLO - avoids system reset during 6V cranking events. |
Use Scenario: Programmable logic controller (PLC) with redundant 24V DC inputs requiring zero-downtime switchover. IC Role / Device Role / Timing Role: LTC3126IUFD#TRPBF serves as intelligent power selector and regulator, validating both inputs and enabling automatic failover within microseconds. Use Value: Delivers 3.3V/2A to CPU core with <50µs switchover time and PGOOD signaling - ensures deterministic real-time operation during input loss. |
| Supercapacitor Backup Supply | Portable Test Equipment |
Use Scenario: Data logger with 5V main supply and supercapacitor-based backup sustaining memory during AC outage. IC Role / Device Role / Timing Role: LTC3126IUFD#TRPBF regulates from supercapacitor (VIN2) after main supply (VIN1) fails, using ideal diode-OR mode for lowest-loss path. Use Value: 2µA Burst Mode quiescent current extends supercapacitor hold-up time to >72 hours; 70mΩ low-side switch minimizes discharge losses. |
Use Scenario: Handheld spectrum analyzer requiring stable 1.8V/2A for ADC and FPGA, powered from USB-C (5V) or Li-ion (3.6–4.2V). IC Role / Device Role / Timing Role: LTC3126IUFD#TRPBF functions as adaptive buck converter with input priority (USB-C preferred) and seamless fallback to battery. Use Value: 200kHz–2.2MHz frequency programming allows optimal inductor selection (2.2µH @ 2MHz) for compact PCB layout without sacrificing efficiency (>92% at 1A). |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-input buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8614EUD#PBF | Single-input, 42V, 4A synchronous buck; no PowerPath or dual-input logic; 2.5µA IQ; 300kHz–3MHz sync capability. | Requires external OR-ing FETs or ideal diodes for dual-source support; lacks VALID/PRIORITY status outputs. | Select when only one input is used and higher current (4A) or faster switching (3MHz) is needed; not suitable for automatic switchover. |
| TPS63070DDCR | Single-input, 16V, 2.4A buck-boost; supports 1.8V–12V output; 20µA IQ; no dual-input arbitration or UVLO programming. | Provides wide VIN-to-VOUT flexibility but cannot manage two independent inputs or provide priority logic. | Choose for battery-powered devices needing VIN < VOUT capability (e.g., single-cell Li-ion to 3.3V); unsuitable for automotive dual-rail backup. |
Compared with LT8614EUD#PBF and TPS63070DDCR, the LTC3126IUFD#TRPBF uniquely integrates dual-input validation, programmable UVLO, and PowerPath switchover in a single IC - eliminating discrete diodes, controllers, and monitoring circuitry required by alternatives.
Availability
LTC3126IUFD#TRPBF is available at Aetrix Electronics and suitable for automotive battery backup, industrial uninterruptible power, and portable test equipment requiring stable component supply with guaranteed long-term availability and traceable sourcing.
Supply support for LTC3126IUFD#TRPBF includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Analog Devices acquired Linear Technology in 2017 and maintains its precision analog and power management portfolio. Linear Technology was founded in 1981 and specialized in high-performance linear products, including switching regulators, references, and signal conditioning ICs.
The LTC3126IUFD#TRPBF belongs to Linear's PowerPath™ family of dual-input power managers, designed specifically for mission-critical systems requiring zero-downtime power source transitions in automotive, industrial, and medical applications.
FAQ
What is the operating temperature range for the LTC3126IUFD#TRPBF?
The LTC3126IUFD#TRPBF is specified for –40°C to 125°C junction temperature operation. This industrial-grade rating is confirmed in the Order Information table and Absolute Maximum Ratings section, making it suitable for under-hood automotive and industrial environments where ambient temperatures exceed 85°C.
How does the LTC3126IUFD#TRPBF handle input switchover without output disturbance?
The LTC3126IUFD#TRPBF uses an internal no-loss PowerPath™ architecture that enables sub-50µs automatic switchover between VIN1 and VIN2. During transition, the buck controller maintains regulation by dynamically reconfiguring the power path - eliminating the need for large hold-up capacitors and preventing output rail droop or glitching.
Can the LTC3126IUFD#TRPBF be synchronized to an external clock?
Yes, the LTC3126IUFD#TRPBF supports external synchronization via the PWM/SYNC pin. When an external clock signal (200kHz–2.2MHz) is applied, the device operates in fixed-frequency PWM mode and disables Burst Mode - enabling EMI reduction through frequency alignment with other system clocks.
What is the purpose of the VSET1 and VSET2 pins on the LTC3126IUFD#TRPBF?
The VSET1 and VSET2 pins on the LTC3126IUFD#TRPBF program the undervoltage lockout (UVLO) thresholds for VIN1 and VIN2, respectively. Using resistor dividers from the 1.0V VREF output, designers can set UVLO from 0V to 20V per input - enabling tailored response to mismatched sources such as 12V battery and 24V supply rails.
Does the LTC3126IUFD#TRPBF support EXTVCC bootstrapping, and what benefit does it provide?
Yes, the LTC3126IUFD#TRPBF supports EXTVCC bootstrapping via Pin 4. Connecting EXTVCC to the regulated output (e.g., 3.3V) powers the internal VCC LDO more efficiently than from VIN, reducing quiescent current by up to 5× and improving light-load efficiency - especially valuable in high-VIN/low-VOUT applications like 36V→3.3V conversion.
LTC3126IUFD#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.4V
- Voltage - Input (Max):
- 42V
- Voltage - Output (Min/Fixed):
- 0.818V
- Voltage - Output (Max):
- 42V
- Current - Output:
- 2.5A
- Frequency - Switching:
- 200kHz ~ 2.2MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-QFN (4x5)
LTC3126IUFD#TRPBF FAQ
1.How can I place an order for LTC3126IUFD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3126IUFD#TRPBF on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LTC3126IUFD#TRPBF reliable?
The price and inventory of LTC3126IUFD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3126IUFD#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3126IUFD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3126IUFD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3126IUFD#TRPBF?
LTC3126IUFD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3126IUFD#TRPBF order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LTC3126IUFD#TRPBF?
For technical support, including LTC3126IUFD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3126IUFD#TRPBF requirements.
6.How does Aetrix verify that LTC3126IUFD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3126IUFD#TRPBF products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LTC3126IUFD#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3126IUFD#TRPBF?
All LTC3126IUFD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3126IUFD#TRPBF, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LTC3126IUFD#TRPBF part is unused and in its original packaging.
Return procedure for LTC3126IUFD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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